For years, Saudi Arabia has vowed to intervene in the oil market only in concert with OPEC bigwigs — and rarely, if ever, alone.

Call it the oil version of "all for one, one for all.” On Sunday, Riyadh threw away its own rule book, announcing a unilateral output cut that would push the country’s production down to levels rarely seen in the last decade.

The market reaction? Meh. Oil rose a lackluster 2% in early trading on Monday, with Brent still below $80 a barrel.